Cellular wireless is an increasingly popular means of personal communication in the modern world. People are using cellular wireless networks for the exchange of voice and data over such devices as cellular telephones, personal digital assistants (PDAs), cellular modems, and other mobile stations.
In a typical cellular wireless communication system, an area is divided into cells and cell sectors, each defined by a radiation pattern (on a particular frequency) from a respective base station or “base transceiver station.” Each base station is then typically connected with core network equipment that functions to provide connectivity with a transport network such as the public switched telephone network (PSTN) or the Internet for instance, and that may function to control base station operation and handoff of served client devices from one base station to another. Conveniently with this arrangement, a cellular phone or other mobile station that is positioned within the coverage area of a given sector can communicate over an air interface with the base station and in turn via the core network equipment with entities on the transport network.
Mobile stations and base stations generally communicate with each other over a radio frequency (RF) air interface according to a defined air interface protocol, examples of which include CDMA, iDEN, WiMAX, TDMA, AMPS, GSM, GPRS, UMTS, EDGE, LTE, WI-FI, BLUETOOTH, and others now known or later developed. Such air interface communication typically occurs on a frequency known as a “carrier” (which may actually be a pair of frequencies, one for forward link communications from the base station to the mobile station, and another for reverse link communication from the mobile station to the base station). On such a carrier, the base station may emit a pilot signal, which is a control signal that a mobile station may detect as an indication of base station coverage. In particular, as the mobile station moves into the coverage of a base station and is operating on the base station's carrier, the mobile station may detect the base station's pilot signal. In response, the mobile station may then hand off to operate in the indicated coverage area. A wireless service provider typically operates numerous base stations in a given geographic region, to provide robust air interface coverage as mobile stations move from one location to another.